It is known to provide cable support blocks for temporarily supporting power conducting or telecommunication cables or the like, while stringing the cable and installing same. A number of support blocks are temporarily installed on a suspended cable during the stringing/installation operations of a new cable supported by the support blocks, and are to be removed afterwards, once the new cable is permanently attached to the upright cable support posts which are driven in the ground. Thus, a support block allowing easy and quick installation and removal thereof is an asset.
U.S. Pat. No. 4,549,723 issued in 1985 to C. R. Castilano discloses a cable support block which comprises a rigid bracket which can be hooked onto an upper support strand which is spacedly supported over ground by successive upright cable support posts. The lower portion of the bracket is provided with a roller which can support the new cable to be installed or stringed. The roller, being rotatably mounted onto the bracket, allows the new cable to be attached to and tensioned between the successive fixed posts while maintaining minimum friction between the support block and the new cable. Indeed, the workperson installing or stringing the new cable does not have to exert great efforts to pull on the new cable for tightening same between the upright posts, since it can roll on the rollers of the spaced cable support blocks.
To prevent the new cable or the support strand from accidental disengagement from the cable support block, a manually operable pivotable elbowed closure arm is provided on the bracket, which can be pivoted between an open position, in which it is upwardly spaced from the roller and allows access to the new cable and to the support strand to and from the roller, and a closed position, in which it comes in close proximity with the roller, so as to trap the new cable and the support strand in the closed area defined by the combination of the roller, the bracket and the closure arm. A manually operable lever is provided to pivot the closure arm. In use, downward pivotal diplacement of the closure arm will have a dual effect: firstly, the support strand will be clamped by the cam member linked to the lever against the upper hooks, for securely releasably attaching the cable support block to the support strand; and secondly, the closure arm will be correspondingly pivoted into its downward closed position, to prevent accidental escape of the cables from within the support block.
A first disadvantage of the cable support block of the Castilano patent is that it is not substantially symmetrical relative to a vertical plane coinciding with the support strand. Indeed, as seen in front elevation, the bracket and the manual lever are located almost entirely on one side of the cable support block, while only the closure arm partially extends on the side opposite the bracket. The V-shaped hooks and the roller are substantially centered in front elevation, relative to the said vertical plane. This assymmetrical configuration is not desirable, since the cable support block may be prone to tilt laterally under its own weight, especially if it is not loaded with the new cable, and thus manipulation of the cable support block becomes more complex for temporarily installing thereon the new cable.
The main disadvantage of the cable support block of the Castilano patent is that the closure arm does not allow quick and easy access of the new cable onto the supporting roller. Indeed, the closure arm requires forcible operative pivotal displacement of the lever from a substantially upright position into a downward position for concurrently pivoting the closure arm. This downward pivotal displacement requires forcible manual intervention by a workperson at cable height, which requires a human operator to be lifted within an aerial basket or the like device at cable height to install/remove the cable support block. This can become a tedious and time consuming operation, especially in areas where there is irregular terrain under the cables which requires vehicles equipped with aerial baskets to move at a slower pace. Moreover, this operation at cable height can become hazarardous to the workperson, since he will come in close proximity with the upper strand, which can be a power conducting line. When such a case occurs, serious physical injury to the workperson can occur if he gets electrocuted. Also, the person operating high above ground level is prone to accidentally falling from his aerial basket and being seriously injured under a high-velocity impact with the ground.
It is known to provide a support block which is similar to the one shown in the Castilano patent, but which lacks the closure arm disclosed therein. The support block is configured so as to be releasably engageable at the end portion of a conventional telescopic pole used by workpersons installing power lines. The pole allows a workperson to distally handle the support block from ground level, to install/remove the support blocks without leaving ground level. Injury likelihood is significantly reduced since no aerial operations need to be accomplished near the potentially power-conducting cables, at cable height. However, such conventional support blocks have an important disadvantage. Indeed, the fact that there is no closure arm allows the new cable being installed to accidentally escape its engagement upon the support block roller and fall down, and also allows the support block to accidentally fall from the support strand. This is highly undesirable, and the closable support block of the Castilano patent has been designed to circumvent this problem.
U.S. Pat. No. 3,837,623 issued in 1974 to W. H. Chadwick, Jr., describes a bundle block which is especially adapted to be used in stringing conductors, with a pilot or pulling line being supported and gradually released by a helicopter. The Chadwick patent includes a frame supporting three axially adjacent rollers, and a guide arm laterally extending in an upwardly inclined fashion from the axially outward extremity of the rollers. The frame defines an opening allowing access to the tangentially upper portion of the rollers, and a gate finger is pivotable on the frame to close this opening. Indeed, a torsion spring continuously urges the gate finger into a closed position, in which the finger abuts against a horizontal detent pin. In use, the line or cable is released by the helicopter and downwardly slides along the upwardly inclined guide arm to abut against the pivotable gate finger. Under the load of the cable, the pivotable gate finger is pivoted into an opened position against the action of the torsion spring, thus allowing access to the cable onto the upper portion of the rollers, to be rollably supported thereby. Once the cable slides onto the roller, the gate finger is released to be urged into its closed position by the torsion spring. Thus, accidental escape of the cable from within the area defined by the combination of the frame, the rollers and the gate finger, is prevented, since the frame opening is closed by the gate finger which outwardly abuts against the fixed detent pin.
The Chadwick bundle block thus allows easy engagement of the cable therein, without requiring manual intervention to open the detent pin. However, it does not allow an easy disengagement of the cable therefrom, since the gate finger must be manually forcibly pivoted against the action of the torsion spring to allow the cable to be removed therefrom. Thus, intervention by a workperon at cable height is required, with the above-mentioned disadvantages. If many bundle blocks such as the one shown in the Chadwick patent were to be used for supporting the cable being stringed, the removal of the bundle blocks would become a tedious and time consuming operation, in addition to being hazardous to the workpersons accomplishing this operation, due to the height at which the operation is being accomplished and to the proximity of the power-conducting lines.